
<template>
  <div class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>考试时间</th>
            <th>操作</th>
          </tr>
        </thead>
        <tbody>
          <tr v-for="(item, index) in list" :key="item.id">
            <td>{{index+1}}</td>
            <td>{{item.subject}}</td>
            <!-- 原本是class="red" -->
            <!-- 现在改为:class="{red: item.score<60} 用的是key：value的方式 -->
              <!-- 当然也可以用三元表达式:class="item.score<60?'red':''" -->
            <td :class="{red: item.score<60}">{{item.score}}</td>
            <!-- 新增formateDate() -->
            <td>{{formateDate(item.date)}}</td>
            <td><a href="#" @click.prevent="delFn(item.id)">删除</a></td>
          </tr>
          <!-- <tr >
            <td>1</td>
            <td>语文</td>
            <td class="red">56</td>
            <td>Tue Jun 07 2022 10:00:00 GMT+0800 (中国标准时间)</td>
            <td><a href="#">删除</a></td>
          </tr>
          <tr >
            <td>2</td>
            <td>数学</td>
            <td>100</td>
            <td>Tue Jun 07 2022 10:00:00 GMT+0800 (中国标准时间)</td>
            <td><a href="#">删除</a></td>
          </tr> -->
        </tbody>
        <!-- <tbody >
          <tr>
            <td colspan="5">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody> -->
        <tfoot>
          <tr>
            <td colspan="5">
              <!-- 321改为{{sumScore}} -->
              <!--...改为 {{avgScore}} 但此时会发现删完平均分会变NaN，因为0/0了，所以要把avgScore变为三元表达式-->
              <span>总分：{{sumScore}}</span>
              <span style="margin-left:50px">平均分：{{avgScore}}</span>
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <!-- 新增v-model.trim="subject" -->
          <input v-model.trim="subject" type="text" placeholder="请输入科目" />
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <!-- 新增v-model.number="score" -->
          <input v-model.number="score" type="text" placeholder="请输入分数" />
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <!-- 新增@click="addFn" -->
          <button class="submit" @click="addFn">添加</button>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
// 新增import moment from "moment";
// 前要在终端里安装moment包：
// npm i moment
import moment from "moment";
export default {
  name: 'ScoreCase',
  data () {
    return {
      list:JSON.parse(localStorage.getItem('score-case')) ||[],
      // list: [
      //   {id: 15, subject: '语文', score: 89, date: new Date('2022/06/07 10:00:00')},
      //   {id: 27, subject: '数学', score: 100, date: new Date('2022/06/07 15:00:00')},
      //   {id: 32, subject: '英语', score: 56, date: new Date('2022/06/08 10:00:00')},
      //   {id: 41, subject: '物理', score: 76, date: new Date('2022/06/08 10:00:00')}
      // ],
      subject: '',
      score: ''
    }
    
  },
  computed:{
    sumScore(){
      return this.list.reduce((sum,item)=>sum+item.score,0)
    },
    avgScore(){
      // return (this.sumScore/this.list.length).toFixed(2)  
      //上面这样全删完会变NaN，所以要变下面：
      return this.list.length?(this.sumScore/this.list.length).toFixed(2):0

    }
    
  },
  methods:{
        delFn(id){
          //console.log(id);
          //①根据id找到索引
          // const index= this.list.findIndex(item=>item.id===id)
          // this.list.splice(index,1)
          //第一种方法略繁琐
          //②filter
          this.list=this.list.filter(item=>item.id!==id)
        },
        formateDate(dt){
          return moment(dt).format("YYYY-MM-DD HH:mm:ss")
        },
        addFn(){
          //this.subject科目不能为空，要有科目
          if(this.score>=0 && this.score<=100 && this.subject){
            this.list.push({ 
              //有元素的话，拿到最后一位的id+1   
              //没元素的话，就是1         
              id:this.length?this.list.at(-1).id+1:1,
              subject:this.subject,
              score:this.score,
              date:new Date()
            })
          }else{
            alert('您输入的不正确')
          }
        }

    },
    watch:{
      list:{
        deep:true,
        handler(){
          //存
          localStorage.setItem('score-case',JSON.stringify(this.list))
          //页面中检查application，storage，localstorage，点网址即可看见存的数据
        }
      }
    }

};
</script>

<style lang="less">
.score-case {
  width: 1000px;
  margin: 50px auto;
  display: flex;
  .table {
    flex: 4;
    table {
      width: 100%;
      border-spacing: 0;
      border-top: 1px solid #ccc;
      border-left: 1px solid #ccc;
      th {
        background: #f5f5f5;
      }
      tr:hover td {
        background: #f5f5f5;
      }
      td,
      th {
        border-bottom: 1px solid #ccc;
        border-right: 1px solid #ccc;
        text-align: center;
        padding: 10px;
        &.red {
          color: red;
        }
      }
    }
    .none {
      height: 100px;
      line-height: 100px;
      color: #999;
    }
  }
  .form {
    flex: 1;
    padding: 20px;
    .form-item {
      display: flex;
      margin-bottom: 20px;
      align-items: center;
    }
    .form-item .label {
      width: 60px;
      text-align: right;
      font-size: 14px;
    }
    .form-item .input {
      flex: 1;
    }
    .form-item input,
    .form-item select {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      width: 200px;
      height: 40px;
      box-sizing: border-box;
      padding: 10px;
      color: #666;
    }
    .form-item input::placeholder {
      color: #666;
    }
    .form-item .cancel,
    .form-item .submit {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      border-radius: 4px;
      padding: 4px 10px;
      margin-right: 10px;
      font-size: 12px;
      background: #ccc;
    }
    .form-item .submit {
      border-color: #069;
      background: #069;
      color: #fff;
    }
  }
}
</style>